I mean...R2-D2 was kind of stupid too.
How the fuck is he rolling around in the desert on some tiny ass wheels? I could understand if they were deep into the third movie and were like "oh shit, we're committed to his form, but we gotta shoot this scene so lets just let it slide", but that's the second god damned scene.
And why do you need a droid to go inside your fighter anyways? Just give that thing its own computer. If R2-D2 made it from the prequels all the way to episode IV, then computer technology is clearly at a commodity level. Oh...but what about how he makes some repairs with his little welding arm? Just put a few little welding arms in key locations on your ship.
What if you forget your droid? Or are racing back to the hanger and it can't keep up with you because it can't jump over a few dead bodies?
And if R2 units are so common why is a 40 year old R2 unit capable of just walking up to any data port on any planet, sticking its probe inside, and unlocking random doors? Are they incapable of implementing any sort of network security? Why even have locks?